WO2019026191A1 - Image capture device and control method - Google Patents

Abstract

An image capture device is provided with: an illumination unit that generates illumination light consisting of components of a plurality of wavelength bands, each component having a characteristic in accordance with a setting; an image capture unit that captures an image of light from a subject, thereby generating an image signal; a condition setting unit that sets acquisition conditions of spectral information of the subject including conditions related to the operations of the illumination unit and of the image capture unit; an image analysis unit that analyzes the image signal generated, on the basis of the acquisition conditions, by the image capture unit, thereby acquiring the spectral information of the subject; and a determination unit that determines whether the spectral information acquired by the image analysis unit satisfies a termination condition for terminating the acquisition of the spectral information, wherein the condition setting unit changes the acquisition conditions of the spectral information if the determination unit determines that the termination condition is not satisfied.

Description

Imaging device and control method

The present invention relates to an imaging device and a control method.

Conventionally, a multi-band spectral image including three primary colors of R, G, and B has high resolution in the color or wavelength direction, and is used for high color reproduction, object analysis, and the like. As a technique for acquiring spectral information with high accuracy from such a spectral image, a technique is known in which a user selects a desired image from images acquired by irradiating a plurality of different illumination lights and sets an acquisition condition. (See, for example, Patent Document 1).

However, according to the above-described technique, it is not possible to set acquisition conditions of spectral information according to the spectral characteristics of the subject. Therefore, a technique has been disclosed that includes a spectrometer side that measures the spectral characteristics of a subject, sets an acquisition condition according to the measurement result, and captures a spectral image (see, for example, Patent Document 2).

JP, 2015-127777, A Patent No. 5806504 gazette

However, although the technique described in Patent Document 2 sets the acquisition condition of spectral information according to the measurement result of the spectral characteristic of the subject, it can not judge whether the acquisition condition is appropriate or not. Therefore, there has been a demand for a technology capable of acquiring highly accurate spectral information of an object under appropriate acquisition conditions.

The present invention has been made in view of the above, and an object of the present invention is to provide an imaging device and a control method capable of acquiring highly accurate spectral information of an object under appropriate acquisition conditions.

In order to solve the problems described above and to achieve the object, an imaging device according to the present invention includes an illumination unit including components of a plurality of wavelength bands, each component generating illumination light having a characteristic according to the setting; An imaging unit configured to generate an image signal by imaging light from a subject; a condition setting unit configured to set acquisition conditions of spectral information of the subject including conditions related to operations of the illumination unit and the imaging unit; An image analysis unit that analyzes an image signal generated based on the acquisition condition to acquire spectral information of the subject, and an end condition for the spectral information acquired by the image analysis unit to end acquisition of the spectral information And a determination unit that determines whether or not the condition is satisfied, and the condition setting unit changes the acquisition condition of the spectral information when the determination unit determines that the end condition is not satisfied. Do

The imaging apparatus according to the present invention is characterized in that, in the above-mentioned invention, the condition setting unit sets a photographing condition at the time of main photographing by the imaging unit when the judgment unit judges that the termination condition is satisfied. .

The imaging apparatus according to the present invention is characterized in that, in the above-mentioned invention, the condition setting unit can selectively set any one of the plurality of acquisition conditions.

The imaging device according to the present invention is characterized in that, in the above-mentioned invention, the condition setting unit improves sensitivity of at least a part of wavelength bands in the image signal when changing the acquisition condition.

The imaging apparatus according to the present invention is characterized in that, in the above-mentioned invention, the condition setting unit determines a wavelength band for improving the sensitivity based on a signal value of the image signal.

The imaging apparatus according to the present invention is characterized in that, in the above invention, the condition setting unit improves wavelength resolution of at least a part of wavelength bands in the image signal when changing the acquisition condition.

The imaging device according to the present invention is characterized in that, in the above-mentioned invention, the condition setting unit determines a wavelength band for improving the wavelength resolution based on a change in signal value of the image signal.

In the imaging device according to the present invention, in the above-mentioned invention, the illumination unit may be a flat filter whose light transmission center wavelength continuously changes along a preset direction, and a side from which light is emitted from the filter A liquid crystal portion that selectively transmits a part of the wavelength band of the light transmitted through the filter, and a light emission portion located on the side from which the light is emitted from the liquid crystal portion, and diffusing the light transmitted through the liquid crystal portion And a diffusion optical system that makes the light uniform, and the liquid crystal unit is capable of changing the wavelength band of light to be transmitted.

A control method according to the present invention generates an image signal by capturing an image of light from an object, using an illumination unit that generates illumination light that is composed of components of a plurality of wavelength bands and each component has a characteristic according to a setting. A control method executed by an imaging apparatus including an imaging unit, wherein a condition setting step of reading and setting acquisition conditions of spectral information of the subject including a condition regarding operations of the illumination unit and the imaging unit. An image signal generation step of generating the image signal based on the acquisition condition, and an image analysis step of analyzing the image signal generated in the image signal generation step to acquire spectral information of the subject. A determination step of determining whether or not the spectral information acquired in the image analysis step satisfies an end condition; and the end condition is not satisfied in the determination step. When it is determined, a condition changing step of changing the acquisition condition of the spectral information, on the basis of the conditions changed by the condition change step, and executes the image signal generating step and the image analysis step again.

According to the present invention, it is possible to acquire highly accurate spectral information of an object under appropriate acquisition conditions.

FIG. 1 is a block diagram showing a configuration of an imaging device according to Embodiment 1 of the present invention. FIG. 2 is a diagram schematically showing the characteristics of the wavelength selection filter. FIG. 3 is a view schematically showing the transmittance of light at representative positions of the wavelength selection filter. FIG. 4 is a diagram showing a setting example of a region where the liquid crystal part transmits light. FIG. 5 is a flowchart showing an outline of processing until the imaging device according to Embodiment 1 of the present invention acquires spectral information of a subject and sets conditions for main shooting. FIG. 6 is a diagram for explaining an operation example of the illumination unit at the time of pre-shooting. FIG. 7 is a diagram showing the relationship between the light amount when the illumination unit emits illumination light and the spectral information calculated by the image analysis unit based on the image signal. FIG. 8 is a diagram showing an example of changing the acquisition condition and spectral information acquired after the change of the acquisition condition. FIG. 9 is a diagram showing an example of changing the acquisition condition performed by the condition setting unit when the end condition is not satisfied in the first modification of the first embodiment of the present invention and spectral information acquired after the acquisition condition is changed. FIG. 10 is a diagram showing an example of changing the acquisition condition performed by the condition setting unit when the end condition is not satisfied and the spectral information acquired after the change of the acquisition condition in the second modification of the first embodiment of the present invention. FIG. 11A shows that the imaging device according to Embodiment 2 of the present invention performs illumination light having components of four bands equal to each other in the light amount of the transmission center wavelength and the half width as an initial state to perform two pre-shootings. It is a figure (the 1) which shows the relationship between the spectral information in the case of, and a wavelength. FIG. 11B shows that the imaging device according to Embodiment 2 of the present invention performs illumination light having components of four bands having the same light intensity at the transmission center wavelength and the half bandwidth equal to each other in the initial state to perform two pre-shootings. It is a figure (the 2) which shows the relationship between the spectral information in the case of, and a wavelength. FIG. 12A is acquired according to the acquisition condition changed by the condition setting unit and the acquisition condition when it is determined that the spectral information does not satisfy the termination condition by the determination unit of the imaging apparatus according to Embodiment 2 of the present invention It is a figure (the 1) showing spectral information. FIG. 12B is acquired according to the acquisition condition changed by the condition setting unit and the acquisition condition when it is determined that the spectral information does not satisfy the termination condition by the determination unit of the imaging device according to Embodiment 2 of the present invention It is a figure (the 2) showing spectral information. FIG. 13A is acquired according to the last acquisition condition set by the condition setting unit and the acquisition condition when it is determined that the spectral information satisfies the end condition by the determination unit of the imaging apparatus according to Embodiment 2 of the present invention It is a figure (the 1) showing the spectrum information which was carried out. FIG. 13B is acquired according to the last acquisition condition set by the condition setting unit and the acquisition condition when it is determined that the spectral information satisfies the end condition by the determination unit of the imaging apparatus according to Embodiment 2 of the present invention It is the figure which shows the spectrum information which is done (the 2). FIG. 14A shows spectral information of two subjects individually acquired by irradiating an illumination light having four bands of components having the same amount of light at the transmission center wavelength and the half bandwidth equal to each other with the imaging device according to Embodiment 3 of the present invention It is a figure which shows the relationship of a wavelength. FIG. 14B is a diagram showing a relationship between spectral information and wavelengths of two objects acquired after the condition setting unit of the imaging device according to Embodiment 3 of the present invention changes the acquisition condition. FIG. 15A shows the relationship between wavelength and spectral information obtained by the imaging device according to Embodiment 4 of the present invention emitting illumination light having four band components having equal light intensity and half bandwidth at the transmission center wavelength. FIG. FIG. 15B shows the relationship between the wavelength and the spectral information obtained by the imaging device according to Embodiment 4 of the present invention emitting illumination light in which the maximum light amounts of the two bands whose spectral information has reached the saturation value are reduced. FIG. FIG. 15C is a diagram showing the relationship between the spectral information and the wavelength acquired by the imaging device according to Embodiment 4 of the present invention emitting illumination light in which the half width of the illumination light at the transmission center wavelength is narrowed. FIG. 16 is a view showing the relationship between the light receiving sensitivity of the image pickup device imaging device according to Embodiment 5 of the present invention, and the light amount of illumination light emitted from the illumination unit and the wavelength.

Hereinafter, a mode for carrying out the present invention (hereinafter, referred to as “embodiment”) will be described with reference to the attached drawings.

Embodiment 1
FIG. 1 is a block diagram showing a configuration of an imaging device according to Embodiment 1 of the present invention. The imaging device 1 shown in the figure includes an imaging unit 2, a lighting unit 3, an input unit 4, an output unit 5, a control unit 6, and a storage unit 7.

The imaging unit 2 photoelectrically converts light from the subject formed by focusing the light from the subject by imaging the imaging optical system 21 that collects light from the subject and forms an imaging signal. And an element 22. The imaging optical system 21 is configured using one or more lenses. The imaging device 22 is configured using, for example, a monochrome image sensor such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). The imaging device 22 may be an image sensor having R, G, B color filters, or may be a multi-band image sensor of four or more bands.

The illumination unit 3 includes a light source unit 31 that outputs white light, and a flat wavelength selection filter (linear variable filter: hereinafter referred to as “LVF”) 32 that transmits white light at different transmission wavelengths according to the incident position. The liquid crystal unit 33 is located on the side where light is emitted from the LVF 32 and selectively transmits a predetermined wavelength band of the light transmitted through the LVF 32, and the liquid crystal unit 33 is located on the side where light is emitted from the liquid crystal unit 33 And diffusive optical system 34 that diffuses the transmitted light and illuminates the light as illumination light.

The light source unit 31 outputs white light using, for example, a light emitting diode (LED) or a laser light source. The light source unit 31 may be configured using a white LED or a white laser, and outputs white light by combining three or more LEDs or lasers including red (R), green (G), and blue (B). It is good also as composition. The light source unit 31 may be configured using a xenon lamp or a halogen lamp.

The LVF 32 has a flat plate shape, and the transmission center wavelength of light continuously changes along the preset direction of the main surface. FIG. 2 is a diagram schematically showing the characteristics of the LVF 32, and is a diagram showing the relationship between the position in the filter and the transmission center wavelength at which the transmittance is the highest. The two opposing sides parallel to the direction of LVF32 a lateral direction in FIG. 2 as the x-axis direction, x = 0 the position of the left edge of LVF32, the right end position and x = x _max. LVF32 the position of the x-axis direction as it changes from x = 0 to x = x _max, the transmission center wavelength λ at each position is increased continuously and linearly (see line L in FIG. 2). The wavelength band λ _min ≦ λ ≦ λ _max is a visible region. For example, the transmission center wavelength lambda _min at the left end x = 0 is 380 nm, the transmission center wavelength lambda _max at the right end x = x _max is 780 nm. In FIG. 2, the transmission center wavelength at x = x _n (n = 1 to 4; 0 <x _n <x _max ) is λ _n . The four vertical lines described in the LVF 32 in FIG. 2 are virtual lines connecting the positions where the wavelength bands to be transmitted are the same. These lines are orthogonal to the direction in which the transmission center wavelength changes, that is, the x-axis direction in FIG.

FIG. 3 is a view schematically showing the light transmittance at representative positions of the LVF 32. As shown in FIG. In FIG. 3, the transmittance of light transmitting each of x = 0, x _n (n = 1 to 4) and x _max is schematically shown. For example, the spectrum S _min of light transmitting x = 0 has a transmission center wavelength λ _min . Similarly, the spectrum S _n of the light transmitted through the x = x _n has a transmission center wavelength lambda _n, the spectrum S _max of the light transmitted through the x = x _max has a transmission center wavelength lambda _max. As apparent from FIG. 3, the spectrum of the transmitted light at each position of the LVF 32 is substantially uniform in transmittance at the transmission center wavelength, and substantially uniform in bandwidth.

In addition, you may comprise the illumination part 3 using filters other than LVF. For example, a multicolor LED light source may be used in which a plurality of LEDs of four or more colors outputting light in different wavelength bands are arranged two-dimensionally.

The liquid crystal unit 33 is located on the exit surface side of the LVF 32, and is configured using a liquid crystal panel capable of selectively outputting light of a preset wavelength band from the transmitted light transmitted through the LVF 32. The liquid crystal unit 33 can selectively switch transmission / non-transmission of incident light for each region by changing the state of liquid crystal molecules in each region under the control of the control unit 6. The transmission wavelength band of the LVF 32 and the incident position of the liquid crystal unit 33 are associated with each other and stored in a position information storage unit 72 of the storage unit 7 described later.

FIG. 4 is a diagram showing a setting example of a region where the liquid crystal unit 33 transmits light. In FIG. 4, it is schematically shown that the hatched area is an area that transmits light. The horizontal direction in the drawing corresponds to the wavelength change direction of the LVF 32. The width of the transmission region in the left and right direction in the drawing corresponds to the width of the wavelength band of the transmitted light. On the other hand, the height in the vertical direction in the figure corresponds to the light amount of the transmitted light. For example, since the second transmission region from the right in FIG. 4 penetrates in the vertical direction, the light amount of the wavelength component included in the transmission region is maximum. In addition, the area | region of the transmitted light may be making shapes other than a rectangle.

The diffusion optical system 34 is configured using, for example, a diffusion plate for diffusing the light flux, or an optical element for homogenizing the light flux diffused by the diffusion plate, and illuminates the light flux obtained by uniforming the illuminance distribution of the light transmitted through the liquid crystal section 33. It illuminates the subject as light.

The illumination unit 3 includes components of a plurality of wavelength bands different from one another, and generates illumination light in which each component has a characteristic according to the setting. The illumination unit 3 sequentially illuminates each component of the illumination light in time division. The number (band number) of the components of the wavelength band included in the illumination light and the half width of each wavelength band can be set by the user inputting via the input unit 4.

The input unit 4 receives input of various signals including an instruction signal for operating the imaging device 1. The input unit 4 includes input devices such as a keyboard, various buttons, various switches, and pointing devices such as a mouse and a touch panel, receives an input of a signal according to an external operation on these devices, and outputs the signal to the control unit 6 . The input unit 4 may have a microphone for voice input.

The output unit 5 outputs various information including an image corresponding to the imaging signal generated by the imaging unit 2. The output unit 5 is configured using liquid crystal, organic EL (Electro Luminescence), or the like, and includes a monitor that outputs various information including images and characters, and a speaker that outputs sound.

The control unit 6 includes an image analysis unit 61, a condition setting unit 62, a determination unit 63, a photographing control unit 64, and a lighting control unit 65.

The image analysis unit 61 acquires spectral information of a subject by analyzing an image using an image signal generated and output by the imaging unit 2. Specifically, the image analysis unit 61 calculates an average of signal values of pixels in a region of interest (ROI) set in advance in an image corresponding to an image signal, and uses this average as spectral information. It is stored in the storage unit 7 in association with the wavelength component of the illumination light at the time of shooting. The region of interest is set by the input unit 4 receiving an input. The region of interest may be the entire image. The image analysis unit 61 may calculate statistical values such as the maximum value or the mode value of the signal values of the pixels in the region of interest instead of the average of the signal values of the pixels in the region of interest. Hereinafter, a statistical value of signal values of pixels in a region of interest as spectral information is referred to as “spectral signal value”.

The condition setting unit 62 sets the imaging condition of the imaging unit 2 and outputs the imaging condition to the imaging control unit 64, and sets the illumination condition of the illumination unit 3 and outputs the illumination condition to the illumination control unit 65. The shooting conditions include a frame rate at the time of shooting and the like. Further, as the illumination condition, there are the number of bands at the time of photographing one image, the central wavelength of the bands, the half width, and the like. The imaging conditions and the illumination conditions constitute acquisition conditions of spectral information and are related to each other. For example, when the illumination unit 3 sequentially illuminates each component of illumination light in time division, the imaging unit 2 captures an image each time the band of the illumination unit 3 is switched, and generates and outputs an imaging signal.

The condition setting unit 62 changes the acquisition condition of the spectral information according to the determination result of the determination unit 63 described later. The condition setting unit 62 changes the sensitivity of at least a part of wavelength bands in the image signal when changing the acquisition condition. Specifically, the condition setting unit 62 increases the maximum light amount of the band having a spectral signal value smaller than a predetermined threshold according to a predetermined rule. The predetermined rule is determined, for example, as a function of the maximum light intensity before the change.

The determination unit 63 determines whether the spectral information acquired by the image analysis unit 61 by the pre-shooting satisfies the end condition for ending the acquisition of the spectral information by the pre-shooting. The termination condition in the first embodiment is, for example, “all spectral signal values are larger than a predetermined threshold”. When the determination unit 63 determines that the end condition is not satisfied, the condition setting unit 62 changes the acquisition condition of the spectral information based on the determination result.

The imaging control unit 64 controls the imaging operation performed by the imaging unit 2 based on the imaging conditions set by the condition setting unit 62.

The illumination control unit 65 controls the operation of the illumination unit 3 in synchronization with the photographing control unit 64 based on the illumination condition set by the condition setting unit 62. Specifically, the illumination control unit 65 controls the transmission pattern of each wavelength component in the liquid crystal unit 33 by controlling the state of the liquid crystal unit 33 at a predetermined timing, and sequentially illuminates multiple bands of illumination light in time division. Control to

The control unit 6 is configured using, for example, a general-purpose processor such as a central processing unit (CPU) or a dedicated integrated circuit that executes a specific function such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). The various arithmetic processes of the imaging device 1 are executed by reading various programs stored in the storage unit 7.

The storage unit 7 stores the filter information storage unit 71 storing transmission characteristics including the wavelength band of the transmitted light at each transmission position of the LVF 32, and position information storing the transmission position of the LVF 32 and the incident position in the liquid crystal unit 33 in association with each other. A storage unit 72, a condition storage unit 73 for storing acquisition conditions of spectral information at the time of pre-shooting, information on changes of the acquisition conditions, end conditions for obtaining spectral information at the time of pre-shooting, and conditions at the time of main shooting It has the image information storage part 74 which memorize | stores the image signal which the part 2 image | photographed, and the spectral information storage part 75 which memorize | stores the spectral information which the image analysis part 61 acquired.

The storage unit 7 also stores a plurality of programs executed by the control unit 6 and various setting information. The program may be written and stored in a computer readable recording medium. The program may be written to the storage unit 7 or the recording medium when the computer or the recording medium is shipped as a product, or may be downloaded through a communication network.

The storage unit 7 is configured using volatile memory such as random access memory (RAM) and non-volatile memory such as read only memory (ROM). The storage unit 7 may be configured using a computer readable recording medium such as a memory card that can be externally mounted.

FIG. 5 is a flowchart showing an outline of processing until the imaging device 1 acquires spectral information of a subject and sets conditions for main imaging. First, the condition setting unit 62 sets an acquisition condition for acquiring spectral information (step S1). The condition setting unit 62 sets an acquisition condition according to, for example, the setting instruction signal received by the input unit 4.

Subsequently, the imaging device 1 performs pre-shooting according to the set acquisition condition (step S2). At this time, the imaging control unit 64 controls the operation of the imaging unit 32 with reference to the condition storage unit 73. Further, the illumination control unit 65 controls the operation of the illumination unit 3 with reference to the filter information storage unit 71, the position information storage unit 72, and the condition storage unit 73. FIG. 6 is a diagram for explaining an operation example of the illumination unit 3 at the time of pre-shooting, and schematically showing a light transmission region of the LVF 32. As shown in FIG. In the case shown in FIG. 6, four bands of illumination light having transmission center wavelengths λ ₁ , λ ₂ , λ ₃ and λ ₄ (λ ₁ <λ ₂ <λ ₃ <λ ₄ ) are sequentially irradiated. The imaging unit 2 performs imaging each time the illumination light of the illumination unit 3 is switched.

Thereafter, the image analysis unit 61 acquires spectral information by analyzing an image signal generated by the imaging unit 2 in advance to generate spectral information and stores the spectral information in the spectral information storage unit 75 (step S3). The spectral information is, as described above, statistical values of pixels in the region of interest set in the image corresponding to the image signal, for example.

FIG. 7 shows the light amount K of the illumination light when the illumination unit 3 irradiates the illumination light as shown in FIG. 6 and the spectral signal in the region of interest, which is the spectral information calculated by the image analysis unit 61 based on the image signal. It is a figure which shows the relationship with the value I. Maximum light amount of the illumination light is the same value K ₁ in all bands. In Figure 7, a spectral signal value when the transmission center wavelength is irradiated with illumination light of lambda _n is set to I _n. I _th shown in FIG. 7 is a predetermined threshold for giving an end condition.

After step S3, the determination unit 63 refers to the condition storage unit 73 to determine whether or not the spectral information satisfies the predetermined end condition (step S4). Exit conditions in the case shown in FIG. 7 is a "spectral signal value I _n of all the bands is larger than the threshold value I _th." In FIG. 7, since the spectral signal values I ₁ and I ₂ are equal to or less than the threshold value I _th , the determination unit 63 determines that the end condition is not satisfied.

As a result of the determination by the determination unit 63, when the spectral information satisfies the termination condition (step S4: Yes), the condition setting unit 62 sets the condition at the time of main shooting and stores the condition in the condition storage unit 73 (step S5). For example, while the condition setting unit 62 sets the number of bands of the illumination unit 3 and the light amount of the transmission center wavelength as the conditions at the time of pre-shooting when the end condition is satisfied, the frame rate at the time of shooting (= one band in the illumination unit 3). The irradiation time) is set to a predetermined frame rate different from that for the pre-shooting. In this way, by setting the conditions at the time of main shooting in consideration of the conditions for pre-shooting that satisfy the end condition, it is possible to acquire an image that matches the spectral characteristics of the subject at the time of main shooting. After step S5, the imaging device 1 ends the series of processes.

In step S4, as a result of the determination by the determination unit 63, when the spectral information does not satisfy the termination condition (step S4: No), the condition setting unit 62 changes the acquisition condition of the spectral information with reference to the condition storage unit 73 ( Step S6). FIG. 8 is a diagram showing a modification example of the acquisition condition and spectral signal values acquired after the change of the acquisition condition. In the case shown in FIG. 8, the condition setting unit 62 sets the light quantity of the illumination light of the transmission center wavelengths λ ₁ and λ ₂ having the spectral signal values I ₁ and I ₂ equal to or less than the threshold value I _{th to} K ₂ larger than the light quantity K _1. It is set to. The quantity K ₂ is a function of the quantity K _1. For example, the light quantity K ₂ is obtained by multiplying a predetermined magnification α (> 1) to the light quantity K _1. Further, in the case illustrated in FIG. 8, the condition setting unit 62 changes the acquisition condition so as to perform the pre-shooting by irradiating the illumination of two bands in which the light amount is changed. By changing the acquisition conditions in this manner, it is possible to accurately acquire spectral information of bands having relatively small spectral signal values. Therefore, it is preferable in the case where information on wavelength components having relatively low spectral signal values is important in determining the characteristics of the subject.

Thereafter, the imaging device 1 returns to step S2 and acquires spectral information again. In the case shown in FIG. 8, two spectral signal values I ₁ ′ and I ₂ ′ respectively acquired again by irradiating the bands of transmission center wavelength λ ₁ and λ ₂ and performing pre-shooting are larger than the threshold I _th . Therefore, in this case, the determination unit 63 determines in step S4 that the spectral information satisfies the end condition. If the determination unit 63 determines that the end condition is not satisfied again, the condition setting unit 62 further changes the acquisition condition and repeats the process after step S2. Specifically, to obtain the spectral information is multiplied by a factor α in quantity K _2.

In addition, when the number of times of change of the acquisition condition exceeds a predetermined number of times, the output unit 5 may output an error message to the effect that spectral information can not be acquired, and the series of processes may be ended. In addition, when the number of times of change of the acquisition condition exceeds the predetermined number, the condition setting unit 62 may set the condition at the time of main photographing based on the latest acquisition condition. By taking these measures, it is possible to suppress an increase in the number of pre-shootings.

According to the first embodiment of the present invention described above, when the spectral information acquired by the image analysis unit does not satisfy the end condition, the condition setting unit changes the acquisition condition of the spectral information, so the acquisition condition is set to It is possible to acquire spectral information of a subject with high accuracy by setting it as appropriate according to the characteristics.

Further, according to the first embodiment, the sensitivity of the wavelength band is increased to improve the S / N ratio by increasing the maximum light amount of the illumination light component of the wavelength band smaller than the threshold, and thus the spectral characteristics of the object. It is possible to acquire highly accurate spectral information according to

Further, according to the first embodiment, since acquisition conditions of spectral information can be appropriately set at the time of pre-shooting, the time during which the user is adjusting the composition and focus for the main shooting is utilized. Control can be performed.

(Modification 1)
The first modification of the first embodiment is different from the first embodiment in the method of changing the end condition and the acquisition condition. The end condition in the first modification is, for example, “whether or not identification with already acquired spectral information or spectral information serving as a reference is possible”. FIG. 9 is a diagram showing an example of changing the acquisition condition performed by the condition setting unit 62 when the end condition is not satisfied, and spectral signal values acquired after changing the acquisition condition. In the case shown in FIG. 9, the condition setting unit 62 emits illumination light of three bands (transmission center wavelengths λ ₅ , λ ₆ , λ ₇ ) different from the illumination light shown in FIG. 7 as acquisition conditions. As a result, the bands shown in FIG. By thus increasing the number of bands of illumination light, wavelength resolution can be improved and more accurate spectral information can be acquired. When pre-shooting is performed after the change, only shooting of the newly added three bands may be performed, or shooting of seven bands including the band before the change may be performed.

In FIG. 9, the newly added band has no overlap with the initial band, but adjacent bands may have an overlap as long as their transmission center wavelengths are different from each other. If the end condition is not satisfied even under the condition shown in FIG. 9, pre-shooting is performed by further increasing the bands having different transmission center wavelengths. In that case, illumination light of a new band whose emission center wavelength is, for example, a wavelength between the adjacent transmission center wavelengths is emitted.

The end condition in the case of changing the acquisition condition so as to increase the number of bands is not limited to the one described above. Further, the method of increasing the number of bands is not limited to the method described above.

(Modification 2)
The second modification of the first embodiment is different from the first embodiment and the first modification in the method of changing the end condition and the acquisition condition. The end condition in the second modification is, for example, "the difference between the maximum value and the minimum value of the spectral signal values is within a predetermined value". FIG. 10 is a diagram showing a modification example of the acquisition condition performed by the condition setting unit 62 when the end condition is not satisfied, and spectral signal values acquired after the acquisition condition is changed. In the case shown in FIG. 10, the condition setting unit 62 performs a change of narrowing the half width of each band according to a predetermined rule as a change of the acquisition condition. In order to narrow the full width at half maximum of each band, it is sufficient to reduce the area of the liquid crystal portion 33 where the transmitted light of the LVF 32 passes. The predetermined rule is given, for example, as a function of half width before change.

If the half value width of each band is narrowed without changing the other conditions, the spectral information is generally smaller than before the change, so that it is possible to suppress spectral signal values that are likely to be saturated. Further, by narrowing the half width, for example, it is possible to improve the determination accuracy in the case where the difference between the maximum value and the minimum value of the spectral information of each band is important in determining the characteristics of the subject.

The end condition in the case of changing the acquisition condition so as to narrow the half width of the band is not limited to the one described above.

(Other modifications)
For example, when information of a band having a relatively large spectral signal value is important, the end condition may be set such that the information of such a band can be accurately acquired, and the method of changing the acquisition condition may be set. . For example, in the case shown in FIG. 7, when the information of the band of the transmission center wavelengths λ ₃ and λ ₄ is important, the light amount of the illumination light of this band may be increased to reacquire spectral information. , transmission center wavelength lambda _3, may be re-acquire the spectral information by increasing the number of bands in the vicinity of lambda _4, the transmission center wavelength lambda _3, the spectral information by increasing the half width in the vicinity of lambda ₄ May be reacquired. Also in these cases, the wavelength resolution can be improved by changing the acquisition condition, and the spectral characteristics of the subject can be acquired with higher accuracy.

Second Embodiment
In the second embodiment of the present invention, two curves are obtained based on spectral signal values as spectral information obtained when two images are pre-photographed by shifting the wavelength of the illumination light of each band by a predetermined amount. The degree of similarity is determined, and the pre-shooting is ended when the degree of similarity falls within a predetermined range. That is, the end condition in the second embodiment is "the similarity between two curves obtained based on the spectral signal values of two images acquired in different bands is within a predetermined range". When this end condition is not satisfied, the number of bands of illumination light is increased and the half width of the band is decreased and two pre-photographs are again performed in the same manner as described above, and Determine the degree of similarity. The above process is repeated until the similarity between the two curves falls within a predetermined range.

The configuration of the imaging device according to the second embodiment is the same as the configuration (see FIG. 1) of the imaging device 1 described in the first embodiment. The outline of processing from setting of acquisition conditions of spectral information to setting of conditions at the time of main photographing is also the same as in the first embodiment (see FIG. 5).

FIGS. 11A and 11B show spectral signal values and wavelengths obtained by performing two pre-shootings by irradiating illumination light having four band components whose light intensity at the transmission center wavelength and half width are equal to each other in the initial state. It is a figure which shows a relation. FIG. 11A shows the relationship between the spectral information and the wavelength when sequentially irradiated with light of four bands having four wavelengths λ ⁽¹⁾ _n (n = 1 to 4) as transmission central wavelengths. In FIG. 11A, polygonal line P ₁₁ obtained by connecting the spectral information adjacent a straight line is a curve of the similarity determination target. FIG. 11B shows the relationship between the spectral signal value and the wavelength when sequentially irradiated with four bands of light having four wavelengths λ ⁽¹⁾ _{n + 4} (n = 1 to 4) as transmission center wavelengths. . In FIG. 11B, polygonal line P ₁₂ obtained by connecting a straight line spectral information adjacent in the same manner as FIG. 11A is a curve of the similarity determination target. The wavelength λ ⁽¹⁾ _{n + 4} is a wavelength obtained by increasing λ ⁽¹⁾ _n by a predetermined amount Δλ ₁ . In the case shown in FIG. 11B, Δλ ₁ is the same for all λ ⁽¹⁾ _n , and Δλ ₁ = (λ ⁽¹⁾ ₂ −λ ⁽¹⁾ ₁ ) / 2.

Determining unit 63 at step S4 in the flowchart shown in FIG. 5, it determines the similarity of the polygonal line P ₁₁ and line P _12. When determining the degree of similarity, the determination unit 63 makes a determination using any of various methods conventionally known. As such a method, for example, a similarity evaluation method using a correlation coefficient, pattern matching of an image, and the like can be raised.

12A and 12B, if the similarity of the polygonal line P ₁₁ and line P ₁₂ by the determination unit 63 is determined not within the predetermined range, that is, in step S4 of the flowchart shown in FIG. 5, the spectral information is end condition It is a figure which shows the acquisition condition which the condition setting part 62 changed, when it determines with not satisfying | fulfilling, and a spectroscopy signal value when pre imaging | photography is carried out according to the acquisition condition. FIG. 12A shows spectral signal values when six wavelengths λ ⁽²⁾ _n (n = 1 to 6) are transmission center wavelengths, and light of a transmission center wavelength and six bands of light having half widths equal to one another are sequentially irradiated. And the relationship between the wavelength. Polygonal line P ₂₁ is obtained by connecting the spectral information adjacent to each other in a straight line. FIG. 12B shows the relationship between the spectral signal value and the wavelength when sequentially irradiated with six bands of light having six wavelengths λ ⁽²⁾ _{n + 6} (n = 1 to 6) as transmission center wavelengths. . Similar to the polygonal line P ₂₂ also polygonal line P _21, obtained by connecting the spectral information adjacent to each other in a straight line. The wavelength λ ⁽²⁾ _{n + 6} is a wavelength obtained by increasing the wavelength λ ⁽²⁾ _n by a predetermined amount Δλ ₂ = (λ ⁽²⁾ ₂ -λ ⁽²⁾ ₁ ) / 2. The full widths at half maximum of each band shown in FIGS. 12A and 12 are all equal and smaller than the full width at half maximum of each band shown in FIGS. 11A and 11B.

Determining unit 63 at step S4 in the flowchart shown in FIG. 5, it determines the similarity of polygonal line P ₂₁ and line P _22. As a result of the determination, if the degree of similarity satisfies a predetermined criterion (step S4: Yes), the process proceeds to setting of the main photographing condition. On the other hand, as a result of the determination, if the degree of similarity does not satisfy the predetermined standard (step S4: No), the condition setting unit 62 changes the acquisition condition again. Hereinafter, the description will be continued as the similarity of the polygonal line P ₂₁ and a line P ₂₂ does not satisfy the termination condition.

As a result of repeating the above processing, when the determination unit 63 determines that the spectral information satisfies the end condition, FIGS. 13A and 13B follow the last acquisition condition set by the condition setting unit 62 and the acquisition condition thereof. It is a figure which shows the spectroscopy signal value at the time of pre imaging | photography. FIG. 13A is a spectral signal when light of 12 bands λ ^(N) _n (n = 1 to 12) is the transmission center wavelength, and light of 12 bands having the same light intensity and half width of the transmission center wavelength is sequentially irradiated. It shows the relationship between the value and the wavelength. The broken line P _N1 is obtained by connecting adjacent spectral information with a straight line. FIG. 13B shows the relationship between the spectral signal value and the wavelength when sequentially irradiated with 12 bands of light having transmission center wavelengths of 12 wavelengths λ ^(N) _{n +12} (n = 1 to 12) respectively. There is. The broken line P _{N2 is} also obtained by connecting adjacent spectral information with a straight line. The wavelength λ ^(N) _{n + 12} is a wavelength obtained by increasing the wavelength λ ^(N) _n by a predetermined amount Δλ _N = (λ ^(N) ₂ -λ ^(N) ₁ ) / 2.

According to the second embodiment of the present invention described above, as in the first embodiment, highly accurate spectral information of an object can be acquired under appropriate acquisition conditions.

Further, according to the second embodiment, two of the spectral signal values of each image obtained when the two images are pre-photographed by shifting the transmission center wavelength of the illumination light of each band by a predetermined amount. In order to determine the degree of similarity of the curves and to change the acquisition condition so as to improve the wavelength resolution until the degree of similarity falls within the predetermined range, it is possible to obtain high-accuracy spectral information according to the spectral characteristics of the subject. it can.

The method of changing the acquisition condition described in the second embodiment is suitable, for example, in the case where the profile of spectral information of a wide band is important in determining the characteristics of a subject.

In the second embodiment, instead of using the curve to be subjected to similarity determination as the above-described broken line, approximation (polynomial approximation) is performed using a curve that passes all spectral information, for example, by using a method such as the least squares method. May be

In the second embodiment, when the acquisition condition is changed, only the number of bands of illumination light may be increased to not change the half width of the band, or the light amount of the transmission center wavelength may be changed along with the number of bands. May be

In the second embodiment, the wavelength may be divided into a plurality of sections, and the determination unit 63 may determine the similarity of the curves in each section. In this case, the condition setting unit 62 may change the acquisition condition so as to narrow the half value width only for the section (non-similar section) determined that the degree of similarity does not fall within the predetermined range.

Third Embodiment
The third embodiment of the present invention calculates the maximum slope of the curve showing the relationship between the wavelength of the illumination light and the spectral signal value of the photographed image, and halves the band of the illumination light until this slope becomes larger than a predetermined slope. Increase the number of bands while narrowing the price range. The configuration of the imaging apparatus according to the third embodiment is the same as the configuration (see FIG. 1) of the imaging apparatus 1 described in the first embodiment. The outline of processing from setting of acquisition conditions of spectral information to setting of conditions at the time of main photographing is also the same as in the first embodiment (see FIG. 5).

FIG. 14A is a diagram showing the relationship between the spectral signal values and the wavelengths of two objects separately pre-photographed by irradiating illumination light having four bands of components having the light intensity of the transmission center wavelength and the half width equal to each other. Polygonal line P ₁₀₁ and P ₁₀₂ are shown in the figure, there is a large difference between the spectral information in the spectral information transmission center wavelength lambda ₃ both in transmission center wavelength lambda _2, are both maximum slope of the broken line. The termination condition in this case is, for example, “the maximum value of the change rate (slope) of the spectral signal value adjacent to the wavelength direction with respect to the wavelength is a predetermined value or more”.

When the polygonal lines P ₁₀₁ and P ₁₀₂ do not satisfy the above-described termination condition (Step S 4 in FIG. 5: No), the condition setting unit 62 changes the acquisition condition (Step S 6 in FIG. 5). Specifically, a section including the transmission center wavelengths λ ₂ and λ ₃ is set as the wavelength band in which the slopes of the broken lines P ₁₀₁ and P ₁₀₂ are maximum, and the number of bands in this section is increased to 6 (transmission Center wavelength: λ ₅ to λ ₁₀ ), narrow the half bandwidth of each band.

FIG. 14B is a diagram showing a relationship between spectral signal values of two subjects obtained by performing preliminary pre-shooting individually after the condition setting unit 62 changes the acquisition condition, and the wavelength. The broken lines P ₂₀₁ and P ₂₀₂ shown in FIG. 14B correspond to the broken lines P ₁₀₁ and P ₁₀₂ respectively. Wavelengths λ ₅ to λ ₁₀ shown in FIG. 14B are transmission center wavelengths of the respective bands based on the changed acquisition conditions. The half width of each band is approximately half of the half width of the band shown in FIG. 14A. Generally, the half width of each band after change is determined as a function having a smaller value than the half width of the band before change.

In FIG. 14B, the maximum inclination of the broken line P _{202 is} the inclination between the transmission center wavelength λ ₅ and the transmission center wavelength λ ₆ . The maximum inclination of the broken line P _{201 is} the inclination between the transmission center wavelength λ ₈ and the transmission center wavelength λ ₉ . These maximum slopes are respectively larger than the maximum slopes of broken lines P ₁₀₁ and P ₁₀₂ shown in FIG. 14A. When it is determined by the determination unit 63 that the maximum inclinations of the broken lines P ₂₀₁ and P ₂₀₂ satisfy the end condition, the imaging device 1 performs the condition setting at the time of main shooting for each subject.

In the case shown in FIG. 14B, the two broken lines P ₂₀₁ and P ₂₀₂ are clearly distinguishable as different broken lines. In this way, the spectral information of the two objects which can not be distinguished in FIG. 14A can be clearly distinguished in FIG. 14B.

According to the third embodiment of the present invention described above, as in the first embodiment, highly accurate spectral information of a subject can be acquired under appropriate acquisition conditions.

Further, according to the third embodiment, it is possible to analyze spectral information with higher accuracy by improving the wavelength resolution of a portion where the change in spectral signal value with respect to the change in wavelength is large.

The third embodiment is suitable for the case where the rate of change of the spectral information with respect to the wavelength and the wavelength band thereof are important in determining the spectral characteristics of the subject.

In the third embodiment, when the number of bands is increased while narrowing the half width of the illumination light band, the increase ratio of the maximum inclination before and after division of the finely divided wavelength section is equal to or less than a predetermined value. The end condition may be

Embodiment 4
The termination condition in the fourth embodiment of the present invention is, for example, "spectral signal values of all bands are not saturated". In the fourth embodiment, as a result of the pre-shooting, the sensitivity is lowered by lowering the maximum light amount among the acquisition conditions for the wavelength band in which the spectral signal value is saturated, and the pre-shooting is performed but is still saturated. Among the acquisition conditions, the pre-shooting is performed by further reducing the sensitivity by narrowing the half width while maintaining the maximum light intensity.

The configuration of the imaging device according to the fourth embodiment is the same as the configuration of the imaging device 1 described in the first embodiment (see FIG. 1). The outline of processing from setting of acquisition conditions of spectral information to setting of conditions at the time of main photographing is also the same as in the first embodiment (see FIG. 5).

FIG. 15A is a diagram showing a relationship between spectral signal values and wavelengths when pre-photographed by irradiating illumination light having four bands of components having the same amount of light at the transmission center wavelength and the half bandwidth equal to each other. FIG. 15A shows a state in which the spectral signal value reaches the saturation value I _max when pre-shooting is performed on two bands having the transmission center wavelengths λ ₃ and λ ₄ respectively. Therefore, in this case, the determination unit 63 determines that the above-described end condition is not satisfied (step S4 in FIG. 5: No).

Thereafter, the condition setting unit 62 reduces the maximum light amount of the band (transmission center wavelengths λ ₃ and λ ₄ ) for which the saturation value is obtained according to a predetermined rule (step S6 in FIG. 5). The predetermined rule is determined, for example, as a function of the maximum light intensity before the change. FIG. 15B shows the relationship between the spectral signal value and the wavelength when pre-photographed by irradiating illumination light in which the maximum light intensity of the two bands for which the spectral signal value has reached the saturation value I _max is K ₄ smaller than K _3. FIG. In the case shown in FIG. 15B, since the spectral signal value obtained by the pre-shooting with the illumination light of the transmission center wavelengths λ ₃ and λ ₄ still reaches the saturation value I _max , the determination unit 63 does not satisfy the end condition described above. It is determined that

Subsequently, the condition setting unit 62 narrows the half bandwidth of the transmission center wavelengths λ ₃ and λ ₄ in accordance with a predetermined rule. The predetermined rule is determined, for example, as a function of the half width before change. FIG. 15C is a diagram showing a relationship between spectral signal values and wavelengths when pre-photographed by irradiating illumination light whose half width is narrowed while the maximum light quantity of the illumination light of the transmission center wavelengths λ ₃ and λ ₄ is K ₄ . It is. In the case shown in FIG. 15C, the spectral signal values of the transmission center wavelengths λ ₃ and λ ₄ are below the saturation value I _max . Therefore, the determination unit 63 determines that the above-described termination condition is satisfied for the first time in the situation illustrated in FIG. 15C.

According to the fourth embodiment of the present invention described above, as in the first embodiment, highly accurate spectral information of a subject can be acquired under appropriate acquisition conditions.

Further, according to the fourth embodiment, by changing the light quantity and the half width alternately to adjust the sensitivity, it is possible to make the saturated spectral signal value an appropriate signal level, and the spectral characteristic is further increased. It becomes possible to judge accurately.

In the fourth embodiment, the condition setting unit 62 reduces the half value width when the value does not fall below the saturation value I _max even if the condition change of reducing the maximum light amount of the transmission center wavelength of the band is repeated a predetermined number of times. Alternatively, the condition change to reduce the maximum light quantity of the transmission center wavelength of the band and the condition change to reduce the half width of the band may be alternately repeated.

In the fourth embodiment, when the condition setting unit 62 changes the acquisition condition a plurality of times, only one of the processing for reducing the maximum light quantity of the transmission center wavelength of the band and the processing for narrowing the half width of the band. It may be performed continuously.

Fifth Embodiment
The imaging unit provided in the imaging apparatus according to Embodiment 5 of the present invention has an image sensor with a color filter as an imaging element. In the fifth embodiment, the sensor sensitivity for each wavelength of the color filter is known, and the transmission center wavelength and half of each band of the illumination light are divided so as to divide the RGB wavelength band into a predetermined number according to the sensor sensitivity. Determine the price range. The configuration of the imaging device excluding the imaging element is the same as the configuration of the imaging device 1 described in Embodiment 1 (see FIG. 1). The outline of processing from setting of acquisition conditions of spectral information to setting of conditions at the time of main photographing is also the same as that of the first embodiment (see FIG. 5).

FIG. 16 is a view showing the relationship between the light receiving sensitivity S of the imaging device of the imaging device according to the fifth embodiment and the light amount K of the illumination light emitted by the illumination unit and the wavelength λ. In FIG. 16, broken lines R, G, and B respectively indicate the sensitivities S of the R component, the G component, and the B component. In the case shown in FIG. 16, the R component, the G component, and the B component of the illumination light are each divided into three bands. The illumination unit 3 illuminates, in time division, partial illumination light in which three bands (Ri, Gi, Bi) (i = 1 to 3) including one color component of the illumination light are included as one set. As a result, the imaging device according to the fifth embodiment emits illumination light of nine bands.

According to the fifth embodiment of the present invention described above, as in the first embodiment, highly accurate spectral information of an object can be acquired under appropriate acquisition conditions.

Further, according to the fifth embodiment, since a part of each color component is simultaneously turned on, light of many bands can be irradiated in a short time. Therefore, the frame rate in the imaging unit can be improved.

In the fifth embodiment, spectral information is obtained by dividing each component of R, G, and B into arbitrary M (M is an integer) band and irradiating illumination light of 3 M band in 1 / M time. May be acquired.

(Other embodiments)
Although the embodiments for carrying out the present invention have been described above, the present invention is not to be limited only by the above-described first to fifth embodiments. For example, the end conditions of the above-described first to fifth embodiments and the method of changing the acquisition conditions may be selectively switched.

The spectral information is not limited to the spectral signal value, and may be any information that reflects the spectral characteristics of the subject and can be acquired from the captured image.

In addition, for a group of subjects having similar spectral characteristics, only one representative subject among them is pre-photographed to determine the condition at the time of main photographing, and based on this condition, all the subjects constituting the group are The main photographing may be performed.

In addition, the end condition is that the rate of change of spectral information with respect to the wavelength is equal to or higher than a predetermined threshold, and the number of bands is reduced in the wavelength section smaller than the threshold, the half bandwidth is increased, or both are implemented. You may As a result, the number of bands at the time of main imaging can be reduced, and speeding up of imaging and reduction of data capacity can be realized.

Thus, the present invention can include various embodiments not described herein, and various design changes can be made within the scope of the technical idea specified by the claims. It is.

Reference Signs List 1 imaging device 2 imaging unit 3 illumination unit 4 input unit 5 output unit 6 control unit 7 storage unit 21 imaging optical system 22 imaging device 31 light source unit 32 LVF
33 liquid crystal unit 34 diffusion optical system 61 image analysis unit 62 condition setting unit 63 determination unit 64 photographing control unit 65 illumination control unit 71 filter information storage unit 72 position information storage unit 73 condition storage unit 74 image information storage unit 75 spectral information storage unit

Claims (9)

1. An illumination unit configured to generate illumination light having components of a plurality of wavelength bands, each component having a characteristic according to a setting;
   An imaging unit that generates an image signal by imaging light from a subject;
   A condition setting unit configured to set an acquisition condition of spectral information of the subject including the condition regarding the operation of the illumination unit and the imaging unit;
   An image analysis unit that analyzes an image signal generated by the imaging unit based on the acquisition condition to acquire spectral information of the subject;
   A determination unit that determines whether the spectral information acquired by the image analysis unit satisfies an end condition for ending the acquisition of the spectral information;
   Equipped with
   The condition setting unit is
   An imaging apparatus characterized in that the acquisition condition of the spectral information is changed when the determination unit determines that the end condition is not satisfied.
2. The condition setting unit is
   The imaging apparatus according to claim 1, wherein when the determination unit determines that the end condition is satisfied, an imaging condition at the time of main imaging by the imaging unit is set.
3. The condition setting unit is
   The imaging apparatus according to claim 1, wherein one of the plurality of acquisition conditions can be selectively set.
4. The condition setting unit is
   The imaging device according to any one of claims 1 to 3, wherein when changing the acquisition condition, sensitivity of at least a part of wavelength bands in the image signal is improved.
5. The condition setting unit is
   The imaging device according to claim 4, wherein a wavelength band for improving the sensitivity is determined based on a signal value of the image signal.
6. The condition setting unit is
   The imaging device according to any one of claims 1 to 5, wherein when changing the acquisition condition, the wavelength resolution of at least a part of wavelength bands in the image signal is improved.
7. The condition setting unit is
   The imaging device according to claim 6, wherein a wavelength band for improving the wavelength resolution is determined based on a change in a signal value of the image signal.
8. The lighting unit is
   A flat filter in which the transmission center wavelength of light varies continuously along a preset direction;
   A liquid crystal unit positioned on the side from which light is emitted from the filter, and selectively transmitting a part of the wavelength band of the light transmitted through the filter;
   A diffusion optical system located on the side from which light is emitted from the liquid crystal unit, and diffusing and homogenizing the light transmitted through the liquid crystal unit;
   Have
   The image pickup apparatus according to any one of claims 1 to 7, wherein the liquid crystal unit is capable of changing a wavelength band of light to be transmitted.
9. An imaging unit comprising: an illumination unit configured to generate illumination light composed of components of a plurality of wavelength bands, each component having a characteristic according to the setting; and an imaging unit configured to generate an image signal by imaging light from a subject A control method executed by the device,
   A condition setting step of reading out and setting acquisition conditions of spectral information of the subject including the conditions relating to the operation of the illumination unit and the imaging unit;
   An image signal generation step of generating the image signal based on the acquisition condition by the imaging unit;
   An image analysis step of analyzing the image signal generated in the image signal generation step to acquire spectral information of the subject;
   A determination step of determining whether or not the spectral information acquired in the image analysis step satisfies an end condition;
   A condition change step of changing the acquisition condition of the spectral information when it is determined in the determination step that the end condition is not satisfied;
   A control method characterized in that the image signal generation step and the image analysis step are executed again based on the condition changed in the condition change step.

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